SOLUTION: A man is five times as old as his son. Four years ago he was nine times as old. Find their present ages.

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Question 826115: A man is five times as old as his son. Four years ago he was nine times as old. Find their present ages.
Answer by JBarnum(2146) About Me  (Show Source):
You can put this solution on YOUR website!
A man is five times as old as his son. Four years ago he was nine times as old. Find their present ages.
For me I use the letter variable of the first letter of the word it stands for to keep it easily understandable in my head.
m=mans age
s=sons age
Ago means past tense so subtraction is required
m=5s
%28m-4%29=9%28s-4%29
Use substitution method
%285s%29-4=9%28s-4%29
Distribute the 9
5s-4=9s-36
Subtract 5s from both sides
-4=4s-36
Add 36 to both sides
32=4s
Divide by 4
8=s
Put back into first equation
m=5%288%29
m=40